Natural and synthetic polymers are being increasingly used under ever more demanding environmental conditions. Flame retardants are commonly used to reduce combustibility of polymeric materials, such as polycarbonates, polyesters and polyamides, has therefore become a pivotal part of the development and application of new materials. (Chen, L., and Wang, Y., Materials, 3: 4746-4760, 2010 and WO2010/132332A1).
Increasing flame retardancy of polymers has been addressed through addition of various flame retardants. For example organophosphorus compounds have been used as flame retardants for polyesters, polyamides and polycarbonates (WO2010/132332A1). Aryl polyphosphonates have been used as flame retardants for polycarbonates and polyamides (Chen, L., supra).
Polyesters such as polytrimethylene terephthalate (PTT), polyethylene terephthalate (PET) and polybutylthylene terephthalate (PBT), find use in many application areas (such as carpets, home furnishings, automotive parts and electronic parts) which require a certain level of flame retardancy. PTT provides desirable attributes such as stretch and recovery, resiliency and stain resistance desirable in face fibers of carpets and is preferred to PET and PBT in such applications. In some carpet construction of PTT fibers do not pass certain standard flammability tests without the use of flame retardant additives.
A number of flame retardants available to date contain various types of halogens (U.S. Pat. No. 4,131,594) which are not environmentally acceptable. A need remains for new flame retardants, particularly non-halogenated flame retardants, for use in polymers.